1. Field of the Invention
The present invention relates to an information processing system, and more particularly to a system recovery method according to which, when an error has developed in a job being online-processed in a certain CPU, the online operation is adapted to continue with a job to be online-processed waiting in another CPU.
2. Description of the Prior Art
As described in "Hot Standby Processing System," 4B-12XDM(10), Preliminary Abstracts of the 32nd (First Term of 1986) National Meeting of the Japan Society of Information Processing, a prior-art system recovery method of the hot standby type is a control method wherein a standby computer is installed as the backup of online computers, and at the time of any failure of the online computer (the failure of a CPU, an operating system, a DB (data base function)/DC (data communication function) or the like, a job having been online-processed is changed to a job to be online-processed waiting in another CPU, thereby to continue the online operation in a moment. Since, however, the wait job for continuing the online operation at the failure is prepared as the backup of the online job for online processing, the online job and the wait job are in the relation of one-to-one correspondence. Accordingly, in a data processing system in which a plurality of online jobs exist, a plurality of wait jobs are correspondingly required, and hence, the wait jobs which are not processed ordinarily except at the failures necessitate a large number of resources such as memories, CPU's and magnetic disk devices. This point is not taken into consideration.
The prior art mentioned above does not take into account the corresponding number of wait jobs in the presence of the plurality of online jobs, and it has the problem that the resources of the information processing system are needed in large quantities because the plurality of existent wait jobs occupy the resources such as memories, CPU's and magnetic disk devices, respectively.